In general, in a building such as a residence, an office building, and a commercial facility, load devices such as air conditioners and lighting devices are widely used in order to adjust a surrounding environment of a user. When a plurality of users are in a space in which an environment is formed by this kind of load device, an agreement may be necessary among the users for determining the operating condition of the load device.
For example, in a case where the load device is an air conditioner and a plurality of users are in a room in which cooling is performed, it is possible that a user who attaches importance to comfort and prefers a lower temperature setting and a user who attaches importance to energy saving and prefers a higher temperature setting may co-exist. In this case, a situation may happen in which an agreement between the users about the temperature setting cannot be reached.
In order to deal with this kind of problem, for example, Japanese Patent Application Publication 2005-172288 (hereinafter referred to as Document 1) proposes an air conditioning apparatus control system that is configured to judge whether a person entering a room is a registered user or not, and to determine, if the person is one of the registered users, the temperature setting so as to reflect the preference of the user. The technique described in Document 1 determines the temperature setting, when there are a plurality of users, by modifying each of preferred temperature ranges that are set respectively for the users using a weighting function so as to take care of potentially disadvantaged or vulnerable users with consideration for the gender and age of each of the users.
Incidentally, in the technique described in Document 1, since the temperature setting is derived by modifying each of preferred temperature ranges that are set respectively for the users using a weighting function according to the priority of each of the users, it may not be possible to set the temperature such that all the users are satisfied. In the technique described in Document 1, the temperature setting is performed in which the preference of a user who is considered to be the vulnerable is prioritized, and the temperature setting cannot be determined taking comfort, energy saving, or the like into consideration. Furthermore, in the technique described in Document 1, since only the temperature is taken into consideration, the technique described in Document 1 can be used for the purpose of determining a temperature setting of an air-conditioner, but cannot be applied to a load device such as a lighting device.